Optical scanning devices are known in particular from the field of computer radiography (CR). A picture of an object, for example a patient or a body part of the patient, is produced here by means of X-ray radiation, and this is stored in a storage phosphor layer as a latent picture. This type of X-ray picture therefore contains X-ray information about the object. In order to read out, i.e. scan, the X-ray information stored in the storage phosphor layer, the storage phosphor layer is stimulated by means of stimulation radiation. As a result of this stimulation, the storage phosphor layer emits light which has an intensity corresponding to the X-ray information stored in the storage phosphor layer. The light emitted from the storage phosphor layer is collected by the scanning device and converted into electric signals which contain an image of the X-ray information. The electric signals are further processed, and the X-ray information stored in the storage phosphor layer is then made visible. The X-ray information can be shown directly on a monitor, for example, or by means of a printer used specially for X-ray pictures, on a photographic X-ray film.
For scanning, an even relative movement is required between the storage phosphor layer and the scanning device. Very stringent requirements exist here with regard to the synchronisation of the relative movement so as to avoid distortion in the X-ray picture.
A driving apparatus for an optical scanning device is known from EP 1 263 207 A1. This driving apparatus includes a cable which is connected to a motor by means of a friction wheel gear. The cable serves to convert the rotary movement of the output shaft of the motor into a linear movement.